Resin and photoresist composition comprising same

ABSTRACT

The present invention provides a resin comprising a structural unit derived from a compound represented by the formula (I): 
     
       
         
         
             
             
         
       
     
     wherein R 1  represents a hydrogen atom or a methyl group, A 2  represents a divalent fluorine-containing C1-C12 hydrocarbon group, and A 1  represents a group represented by the formula (a-g1): 
       A 10 -X 10  s A 11 -  (a-g1)
 
     wherein A 10  is independently in each occurrence a C1-C5 aliphatic hydrocarbon group, A 11  represents a C1-C5 aliphatic hydrocarbon group, X 10  is independently in each occurrence —O—, —CO—, —CO—O— or —O—CO—, and s represents an integer of 0 to 2, and
 
a photoresist composition comprising the resin and an acid generator.

This nonprovisional application claims priority under 35 U.S.C. §119(a)on Patent Application No. 2011-092661 filed in JAPAN on Apr. 19, 2011,the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a resin and a photoresist compositioncomprising the same.

BACKGROUND OF THE INVENTION

A photoresist composition used for semiconductor microfabricationemploying a lithography process contains a resin having a structuralunit derived from a compound having an acid-labile group, beinginsoluble or poorly soluble in an alkali aqueous solution but becomingsoluble in an alkali aqueous solution by the action of an acid, an acidgenerator and a basic compound.

US 2009/020945 A1 discloses a fluorine-containing resin obtained bypolymerizing the monomers represented by the following formulae.

US 2009/020945 A1 also discloses a photoresist composition comprisingthe above-mentioned fluorine-containing resin, a resin obtained bypolymerizing the monomers represented by the following formulae;

and 4-cyclohexylphenyldiphenylsulfonium perfluorobutanesulfonate as anacid generator.

SUMMARY OF THE INVENTION

The present invention is to provide a novel resin and a photoresistcomposition comprising the same.

The present invention relates to the following:

<1> A resin comprising a structural unit derived from a compoundrepresented by the formula (I):

wherein R¹ represents a hydrogen atom or a methyl group, A² represents adivalent fluorine-containing C1-C12 hydrocarbon group, and A¹ representsa group represented by the formula (a-g1):

A¹⁰-X¹⁰_(s)A¹¹-  (a-g1)

wherein A¹⁰ is independently in each occurrence a C1-C5 aliphatichydrocarbon group, A¹¹ represents a C1-C5 aliphatic hydrocarbon group,X¹⁰ is independently in each occurrence —O—, —CO—, —CO—O— or —O—CO—, ands represents an integer of 0 to 2;<2> The resin according to <1>, wherein s is 0 in the formula (a-g1);<3> The resin according to <1> or <2>, wherein A¹¹ is a C1-C6 alkanediylgroup in the formula (a-g1);<4> The resin according to any one of <1> to <3>, wherein A¹¹ is anethylene group in the formula (a-g1);<5> The resin according to any one of <1> to <4>, wherein A² is a C1-C3perfluoroalkanediyl group in the formula (I);<6> The resin according to any one of <1> to <5>, which furthercomprises a structural unit derived from a compound having anacid-labile group;<7> The resin according to <6>, wherein the compound having anacid-labile group is a monomer represented by the formula (a1-1) or(a1-2):

wherein R^(a4) and R^(a5) each independently represents a hydrogen atomor a methyl group, R^(a6) and R^(a7) each independently represents aC1-C8 alkyl group or a C3-C10 alicyclic hydrocarbon group, L^(a1) andL^(a2) each independently represents *—O— or *—O—(CH₂)_(k1)—CO—O— inwhich * represents a binding position to —CO—, and k1 represents aninteger of 1 to 7, and m1 represents an integer of 0 to 14, n1represents an integer of 0 to 10, and n1′ represents an integer of 0 to3;<8> The resin according to any one of <1> to <7>, which furthercomprises a structural unit derived from a compound having noacid-labile group and having a hydroxyladamantyl group;<9> The resin according to <8>, wherein the compound having noacid-labile group and having a hydroxyladamantyl group is a monomerrepresented by the formula (a2-1):

wherein R^(a14) represents a hydrogen atom or a methyl group, R^(a15)and R^(a16) each independently represent a hydrogen atom, a methyl groupor a hydroxyl group, L^(a3) represents *—O— or *—O—(CH₂)_(k2)—CO—O— inwhich * represents a binding position to —CO—, and k2 represents aninteger of 1 to 7, and 01 represents an integer of 0 to 10;<10> The resin according to any one of <1> to <9>, which furthercomprises a structural unit derived from a monomer having no acid-labilegroup and having a lactone ring;<11> The resin according to <10>, wherein the monomer having noacid-labile group and having a lactone ring is a monomer represented bythe formula (a3-1), (a3-2) or (a3-3):

wherein L^(a4), L^(a5) and L^(a6) each independently represent *—O— or*—O—(CH₂)_(k3)—CO—O— in which * represents a binding position to —CO—and k3 represents an integer of 1 to 7, R^(a18), R^(a19) and R^(a20)each independently represent a hydrogen atom or a methyl group, R^(a21)represents a C1-C4 alkyl group, R^(a22) and R^(a23) are independently ineach occurrence a carboxyl group, a cyano group or a C1-C4 alkyl group,and p1 represents an integer of 0 to 5, q1 and r1 independently eachrepresent an integer of 0 to 3;<12> The resin according to any one of <1> to <11>, which furthercomprises a structural unit derived from a monomer having no acid-labilegroup and having one or more fluorine atoms;<13> The resin according to <12>, wherein the monomer having noacid-labile group and having one or more fluorine atoms is a monomerrepresented by the formula (a4-1):

wherein R⁴¹ represents a hydrogen atom or a methyl group, A⁴² representsan optionally substituted C1-C18 aliphatic hydrocarbon group, and A⁴¹represents a group represented by the formula (a4-g1):

A⁴⁰-X⁴⁰_(ss)A⁴³-  (a4-g1)

wherein A⁴⁰ is independently in each occurrence a C1-C5 aliphatichydrocarbon group, A⁴³ represents a C1-C5 aliphatic hydrocarbon group,X⁴⁰ is independently in each occurrence —O—, —CO—, —CO—O— or —O—CO—, andss represents an integer of 0 to 2;<14> A photoresist composition comprising the resin according to any oneof <1> to <13> and an acid generator;<15> The photoresist composition according to <14>, which furthercomprises a solvent;<16> A process for producing a photoresist pattern comprising thefollowing steps (1) to (5):

(1) a step of applying the photoresist composition according to <14> or<15> on a substrate,

(2) a step of forming a photoresist film by conducting drying,

(3) a step of exposing the photoresist film to radiation,

(4) a step of baking the exposed photoresist film, and

(5) a step of developing the baked photoresist film with an alkalinedeveloper, thereby forming a photoresist pattern.

DESCRIPTION OF PREFERRED EMBODIMENTS

First, the resin of the present invention (hereinafter, simply referredto as RESIN (A)) will be illustrated.

RESIN (A) comprises a structural unit derived from a compoundrepresented by the formula (I):

wherein R¹ represents a hydrogen atom or a methyl group, A² represents adivalent fluorine-containing C1-C12 hydrocarbon group, and A¹ representsa group represented by the formula (a-g1):

A¹⁰-X¹⁰_(s)A¹¹-  (a-g1)

wherein A¹⁰ is independently in each occurrence a C1-C5 aliphatichydrocarbon group, A¹¹ represents a C1-C5 aliphatic hydrocarbon group,X¹⁰ is independently in each occurrence —O—, —CO—, —CO—O— or —O—CO—, ands represents an integer of 0 to 2.

Examples of the C1-C5 aliphatic hydrocarbon group represented by A¹⁰include a C1-C5 alkanediyl group, and a C1-C4 alkanediyl group ispreferable. The alkanediyl group may be a linear alkanediyl group or abranched chain alkanediyl group. Examples thereof include a methylenegroup, an ethylene group, a propanediyl group, a butandiyl group, apentanediyl group and a hexanediyl group.

Examples of the C1-C5 aliphatic hydrocarbon group represented by A¹¹include the same as those described in A¹¹. A¹¹ is preferably a C1-C4alkanediyl group, and an ethylene group is more preferable.

Examples of the group represented by the formula (a-g1) include theabove-mentioned C1-C5 aliphatic hydrocarbon group and the following.

wherein * represents a binding position.

The group represented by the formula (a-g1) wherein s is 0 ispreferable, and preferably 0, and the group represented by the formula(a-g1) wherein s is 0 and A¹¹ is a C1-C6 alkanediyl group is morepreferable, and the group represented by the formula (a-g1) wherein s is0 and A¹¹ is a C1-C4 alkanediyl group is especially more preferable.

A¹ is preferably a C1-C6 alkanediyl group, and more preferably a C1-C4alkanediyl group, and especially preferably an ethylene group.

The divalent hydrocarbon group of the divalent fluorine-containingC1-C12 hydrocarbon group represented by A² includes a chain divalenthydrocarbon group, a cyclic divalent hydrocarbon group and a groupformed by combining a chain divalent hydrocarbon group and a cyclicdivalent hydrocarbon group. The divalent C1-C12 hydrocarbon group may besaturated or unsaturated, and preferably saturated. Examples of thechain divalent hydrocarbon group include a C1-C12 alkanediyl group suchas a methylene group, an ethylene group, a propanediyl group, abutanediyl group, a pentanediyl group and a hexanediyl group. The cyclicdivalent hydrocarbon group may be monocyclic or polycyclic, and examplesthereof include a monocyclic hydrocarbon group such as a cycloalkanediylgroup such as a cyclopentanediyl group, a cyclohexanediyl group, acycloheptanediyl group and a cyclooctanediyl group, and a polycyclichydrocarbon group such as a decahydronaphthalenediyl group, anadamantandiyl group, a norbornanediyl group and the following.

wherein * represents a binding position. Examples of the group formed bycombining a chain divalent hydrocarbon group and a cyclic divalenthydrocarbon group include the following.

wherein * represents a binding position.

Examples of the divalent fluorine-containing C1-C12 hydrocarbon grouprepresented by A² include the following.

wherein * represents a binding position.

A² is preferably a C1-C6 perfluoroalkanediyl group, and more preferablya C1-C4 perfluoroalkanediyl group, and still more preferably a C1-C3perfluoroalkanediyl group, and especially preferably aperfluoropropanediyl group.

Examples of the compound represented by the formula (I) include thecompounds represented by the following formulae (I-1) to (1-8).

The compound represented by the formula (I) can be produced by reactinga compound represented by the formula (Is-1) with a compound representedby the formula (Is-2) in the presence of a basic catalyst such aspyridine in a solvent such as tetrahydrofuran.

wherein R¹, A¹ and A² are the same as defined above.

Examples of the compound represented by the formula (Is-1) includehydroxyethyl methacrylate. Examples of the compound represented by theformula (Is-2) include heptafluorobutyric anhydride.

The structural unit derived from the compound represented by the formula(I) means a structural unit represented by the formula (Ia), astructural unit represented by the formula (Ib), or both thereof.

wherein R¹, A¹ and A² are the same as defined above.

The content of the structural unit derived from the compound representedby the formula (I) in RESIN (A) is usually 0.5 to 15% by mole based on100% by mole of all the structural units of RESIN (A), and preferably 1to 10% by mole and more preferably 1 to 5% by mole.

RESIN (A) preferably contains a structural unit derived from a compoundhaving an acid-labile group in addition to the structural unit derivedfrom the compound represented by the formula (I).

RESIN (A) comprising the structural unit derived from a compound havingan acid-labile group is a resin being insoluble Or poorly soluble in anaqueous alkali solution but becoming soluble in an aqueous alkalisolution by the action of an acid.

RESIN (A) can contain two or more kinds of the structural unit derivedfrom a compound having an acid-labile group.

In this specification, “an acid-labile group” means a group capable ofbeing eliminated by the action of an acid.

Examples of the acid-labile group include a group represented by theformula (10):

wherein R^(a1), R^(a2) and R^(a1) independently each represent a C1-C8alkyl group or a C3-C20 alicyclic hydrocarbon group, and R^(a1) andR^(a2) can be bonded each other to form a C2-C20 divalent hydrocarbongroup which forms a ring together with the carbon atom to which they arebonded, and one or more —CH₂— in the C1-C8 alkyl group, the C3-C20alicyclic hydrocarbon group and the C3-C20 divalent hydrocarbon groupcan be replaced by —O—, —S— or —CO—.

Examples of the C1-C8 alkyl group include a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, a pentylgroup, a hexyl group, a heptyl group and an octyl group. The alicyclichydrocarbon group may be monocyclic or polycyclic, and may be saturatedor non-aromatic unsaturated. Examples thereof include a monocyclicalicyclic hydrocarbon group such as a C3-C20 cycloalkyl group (e.g. acyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, adimethylcyclohexyl group, a cycloheptyl group and a cyclooctyl group)and a polycyclic alicyclic hydrocarbon group such as a decahydronaphthylgroup, an adamantyl group, a norbornyl group, a methylnorbornyl group,and the followings:

The alicyclic hydrocarbon group is preferably a saturated cyclichydrocarbon group, and preferably has 3 to 16 carbon atoms.

Examples of the ring formed by bonding R^(a1) and R^(a2) each otherinclude the following groups and the ring preferably has 3 to 12 carbonatoms.

wherein R^(a3) is the same as defined above.

The group represented by the formula (10) wherein R^(a1), R^(a2) andR^(a3) independently each represent a C1-C8 alkyl group such as atent-butyl group, the group represented by the formula (10) whereinR^(a1) and R^(a2) are bonded each other to form an adamantyl ring andR^(a3) is a C1-C8 alkyl group such as a 2-alkyl-2-adamantyl group, andthe group represented by the formula (10) wherein R^(al) and R^(a2) areC1-C8 alkyl groups and R^(a3) is an adamantyl group such as a1-(1-adamantyl)-1-alkylalkoxycarbonyl group are preferable.

Examples of the acid-labile group include a group represented by theformula (20):

wherein R^(b1) and R^(b2) independently each represent a hydrogen atomor a C1-C12 hydrocarbon group, and R^(b3) represents a C1-C20hydrocarbon group, and R^(b2) and R^(b3) can be bonded each other toform a C2-C20 divalent hydrocarbon group which forms a ring togetherwith the carbon atom and the oxygen atom to which they are bonded, andone or more in the hydrocarbon group and the divalent hydrocarbon groupcan be replaced by —O—, —S— or —CO—.

The group represented by the formula (20) has an acetal structure.

Examples of the hydrocarbon group include an aliphatic hydrocarbongroup, an alicyclic hydrocarbon group and an aromatic hydrocarbon group.Examples of the aromatic hydrocarbon group include an aryl group such asa phenyl group, a naphthyl group, an anthryl group, a p-methylphenylgroup, a p-tert-butylphenyl group, a p-adamantylphenyl group, a tolylgroup, a xylyl group, a cumyl group, a mesityl group, a biphenyl group,a phenathryl group, a 2,6-diethylphenyl group and a2-methyl-6-ethylphenyl group.

It is preferred that at least one of R^(b1) and R^(b2) is a hydrogenatom.

Examples of the group represented by the formula (20) include thefollowing.

The compound having an acid-labile group is preferably a monomer havingan acid-labile group in its side chain and a carbon-carbon double bond,and is more preferably an acrylate monomer having an acid-labile groupin its side chain or a methacryalte monomer having an acid-labile groupin its side chain.

A monomer having the group represented by the formula (1q) or (20) inits side chain and a carbon-carbon double bond is preferable, and anacrylate monomer having the group represented by the formula (10) in itsside chain or a methacryalte monomer having the group represented by theformula (10) in its side chain is more preferable.

An acrylate monomer having the group represented by the formula (10) inwhich R^(a1) and R^(a2) are bonded each other to form a C5-C20 alicycletogether with the carbon atom to which they are bonded in its side chainor a methacryalte monomer having the group represented by the formula(10) in which R^(a1) and R^(a2) are bonded each other to form a C5-C20alicycle together with the carbon atom to which they are bonded in itsside chain is especially preferable.

Preferable examples of the compound having an acid-labile group includemonomers represented by the formulae (a1-1) and (a1-2);

wherein R^(a4) and R^(a5) each independently represents a hydrogen atomor a methyl group, R^(a6) and R^(a7) each independently represents aC1-C8 alkyl group or a C3-C10 alicyclic hydrocarbon group, L^(a1) andL^(a2) each independently represents *—O— or *—O—(CH₂)_(k1)—CO—O— inwhich * represents a binding position to —CO—, and k1 represents aninteger of 1 to 7, and m1 represents an integer of 0 to 14, n1represents an integer of 0 to 10, and n1′ represents an integer of 0 to3.

The alkyl group preferably has 1 to 6 carbon atoms, and the alicyclichydrocarbon group preferably has 3 to 8 carbon atoms and more preferably3 to 6 carbon atoms. The alicyclic hydrocarbon group is preferably asaturated aliphatic cyclic hydrocarbon group.

Examples of the C1-C8 alkyl group include a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, a tert-butylgroup, a 2,2-dimethylethyl group, a 1-methylpropyl group, a2,2-dimethylpropyl group, a 1-ethylpropyl group, a 1-methylbutyl group,a 2-methylbutyl group, a 3-methylbutyl group, a 1-propylbutyl group, apentyl group, a 1-methylpentyl group, a hexyl group, a 1,4-dimethylhexylgroup, a heptyl group, a 1-methylheptyl group and an octyl group.Examples of the alicyclci hydrocarbon group include a cyclohexyl group,a methylcyclohexyl group, a dimethylcyclohexyl group, a cycloheptylgroup, a methylcycloheptyl group, a norbornyl group, a methylnorbornylgroup and the following groups.

L^(a1) is preferably *—O— or *—O—(CH₂)_(f1)—CO—O— in which * representsa binding position to —CO—, and f1 represents an integer of 1 to 4, andis more preferably *—O— or *—O—CH₂—CO—O—, and is especially preferably*—O—. L^(a2) is preferably *—O— or *—O—(CH₂)_(f1)—CO—O— in which *represents a binding position to —CO—, and f1 is the same as definedabove, and is more preferably *—O— or *—O—CH₂—CO—O—, and is especiallypreferably *—O—.

In the formula (a1-1), m1 is preferably an integer of 0 to 3, and ismore preferably 0 or 1. In the formula (a1-2), n1 is preferably aninteger of 0 to 3, and is more preferably 0 or 1, and n1′ is preferably0 or 1.

R^(a4) and R^(a5) are preferably methyl groups.

Examples of the monomer represented by the formula (a1-1) include themonomers described in JP 2010-204646 A. Among them, preferred are themonomers represented by the formulae (a1-1-1) to (a1-1-8), and morepreferred are the monomers represented by the formulae (a1-1-1) to(a1-1-4).

Examples of the monomer represented by the formula (a1-2) include1-ethylcyclopentan-1-yl acrylate, 1-ethylcyclopentan-1-yl methacrylate,1-ethylcyclohexan-1-yl acrylate, 1-ethylcyclohexan-1-yl methacrylate,1-ethylcycloheptan-1-yl acrylate, 1-ethylcycloheptan-1-yl methacrylate,1-methylcyclopentan-1-yl acrylate, 1-methylcyclopentan-1-ylmethacrylate, 1-isopropylcyclopentan-1-yl acrylate and1-isopropylcyclopentan-1-yl methacrylate. Among them, preferred are themonomers represented by the formulae (a1-2-1) to (a1-2-10), and morepreferred are the monomers represented by the formulae (a1-2-3) and(a1-2-4), and still, more preferred is the monomer represented by theformula (a1-2-31.

The content of the structural unit derived from a compound having anacid-labile group in RESIN (A) is usually 10 to 95% by mole, preferably15 to 90% by mole and more preferably 20 to 85% by mole based on 100% bymole of all the structural units of the resin.

When the resin contains the structural unit derived from the monomerrepresented by the formula (a1-1) or (a1-2), the content of thestructural unit derived from the monomer represented by the formula(a1-1) or (a1-2) in the resin is usually 10 to 95% by mole based on 100%by mole of all the structural units of RESIN (A), and preferably 15 to90% by mole and more preferably 20 to 85% by mole. The content of thestructural unit derived from a monomer having an adamantyl group,especially the monomer represented by the formula (a1-1) in thestructural unit derived from the compound having an acid-labile group ispreferably 15% by mole or more from the viewpoint of dry-etchingresistance of the photoresist composition.

Other examples of the compound having an acid-labile group include amonomer represented by the formula (a1-5):

wherein R³¹ represents a hydrogen atom, a halogen atom, a C1-C6 alkylgroup which may be substituted with a halogen atom, L¹ represents —O—,—S— or *—O—(CH₂)_(k1)—CO—O—, k1 represents an integer of 1 to 7, *represents a binding position to —CO—, L² and L³ independently eachrepresent —O— or —S—, Z¹ represents a single bond or a C1-C6 alkylenegroup in which one or more —CH₂— may be replaced by —O— or —CO—, s1 ands1′ independently each represent an integer of 0 to 4.

Examples of the halogen atom include a fluorine atom, a chlorine atomand a bromine atom.

Examples of the C1-C6 alkyl group which may be substituted with ahalogen atom include a methyl group, an ethyl group, a propyl group, anisopropyl group, a butyl group, an isobutyl group, a sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, a trifluoromethylgroup, a pentafluoroethyl group, a heptafluoropropyl group, aheptafluoroisopropyl group, a nonafluorobutyl group, anonafluoro-sec-butyl group, a nonafluoro-tert-butyl group, aperfluoropentyl group, a perfluorohexyl group, a perchloromethyl group,a perbromomethyl group and a periodomethyl group, and a C1-C4 alkylgroup is preferable and a C1-C2 alkyl group is more preferable and amethyl group is especially preferable.

R³¹ is preferably a hydrogen atom or a methyl group.

L¹ is preferably —O—.

It is preferred that one of L² and L³ is —O— and the other is —S—.

In the formula (a1-5), 51 is preferably 1 and s1′ is preferably 0, 1 or2.

Z¹ is preferably a single bond, *—(CH₂)_(n4)—O— or *—(CH₂)_(n4)—CO—O— inwhich n4 represents an integer of 1 to 4, and * represents a bindingposition to L⁴, and more preferably a single bond, —CH₂—O— or—CH₂—CO—O—.

Examples of the monomer represented by the formula (a1-5) include themonomers represented by the following formulae) a1-5-19 to (a1-5-4)

When RESIN (A) contains the structural unit derived form the monomerrepresented by the formula (a1-5), the content of the structural unitderived from the monomer represented by the formula (a1-5) is usually 1to 95% by mole and preferably 3 to 90% by mole and more preferably 5 to85% by mole based on total molar of all the structural units of RESIN(A).

RESIN (A) preferably contains the structural unit derived from thecompound having an acid-labile group and a structural unit derived fromthe compound having no acid-labile group. RESIN (A) can have two or morekinds of structural units derived from the compounds having noacid-labile group.

The compound having no acid-labile group preferably contains one or morehydroxyl groups or a lactone ring. When the resin contains thestructural unit derived from the compound having no acid-labile groupand having one or more hydroxyl groups or a lactone ring, a photoresistcomposition having good resolution and adhesiveness of photoresist to asubstrate tends to be obtained.

RESIN (A) preferably comprises a structural unit derived from a compoundhaving no acid-labile group and having a hydroxyladamantyl group.

Examples of the compound having no acid-labile group and having one ormore hydroxyl groups include a monomer represented by the formula (a2-0)

wherein R^(a30) represents a hydrogen atom, a halogen atom or a C1-C6alkyl group which may have one or more halogen atoms, R^(e31) isindependently in each occurrence a halogen atom, a hydroxyl group, aC1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C4 acyl group, a C2-C4acyloxy group, an acryloyl group or a methacryloyl group, ma representsan integer of 0 to 4, anda monomer represented by the formula (a2-1):

wherein R^(a14) represents a hydrogen atom or a methyl group, R^(a15)and R^(a16) each independently represent a hydrogen atom, a methyl groupor a hydroxyl group, L^(a3) represents *—O— or *—O—(CH₂)_(k2)—CO—O— inwhich * represents a binding position to —CO—, and k2 represents aninteger of 1 to 7, and o1 represents an integer of 0 to 10.

When KrF excimer laser (wavelength: 248 nm) lithography system, or ahigh energy laser such as electron beam (EB) and extreme ultraviolet(EUV) is used as an exposure system, RESIN (A) containing the structuralunit derived from the monomer represented by the formula (a2-0) ispreferable, and when ArF excimer laser (wavelength: 193 nm) is used asan exposure system, RESIN (A) containing the structural unit derivedfrom the monomer represented by the formula (a2-1) is preferable.

In the formula (a2-0), examples of the halogen atom include a fluorineatom, examples of the C1-C6 alkyl group which may have one or morehalogen atoms include a methyl group, an ethyl group, propyl group, anisopropyl group, a butyl group, an isobutyl group, a sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, a trifluoromethylgroup, a pentafluoroethyl group, a heptafluoropropyl group, aheptafluoroisopropyl group, a nonafluorobutyl group, anonafluoro-sec-butyl group, a nonafluoro-tert-butyl group, aperfluoropentyl group and a perfluorohexyl group, and a C1-C4 alkylgroup is preferable and a C1-C2 alkyl group is more preferable and amethyl group is especially preferable. Examples of the C1-C6 alkoxygroup include a methoxy group, an ethoxy group, a propoxy group, anisopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxygroup, a text-butoxy group, a pentyloxy group and a hexyloxy group, anda C1-C4 alkoxy group is preferable and a C1-C2 alkoxy group is morepreferable and a methoxy group is especially preferable. Examples of theC2-C4 acyl group include an acetyl group, a propionyl group and abutyryl group, and examples of the C2-C4 acyloxy group include anacetyloxy group, a propionyloxy group and a butyryloxy group. In theformula (a2-0), ma is preferably 0, 1 or 2, and is more preferably 0 or1, and especially preferably Q.

RESIN (A) containing the structural unit derived from the monomerrepresented by the formula (a2-0) can be produced, for example, bypolymerizing a monomer obtained by protecting a hydroxyl group of themonomer represented by the formula (a2-0) with a protecting group suchas an acetyl group followed by conducting deprotection of the obtainedpolymer with a base.

Examples of the monomer represented by the formula (a2-0) include themonomers described in JP 2010-204634 A, and the monomers represented bythe formulae (a2-0-1) and (a2-0-2)

When RESIN (A) containing the structural unit derived from the monomerrepresented by the formula (a2-0) is produced, a monomer of whichhydroxyl group is protected with a suitable protecting group can beused.

When RESIN (A) contains the structural unit derived from the monomerrepresented by the formula (a2-0), the content of the structural unitderived from the monomer represented by the formula (a2-0) is usually 5to 90% by mole and preferably 10 to 85% by mole and more preferably 15to 80% by mole based on total molar of all the structural units of RESIN(A).

In the formula (a2-1), R^(a14) is preferably a methyl group, R^(a15) ispreferably a hydrogen atom, R^(a16) is preferably a hydrogen atom or ahydroxyl group, L^(a3) is preferably *—O— or *—O—(CH₂)_(f2)—CO—O— inwhich * represents a binding position to —CO—, and f2 represents aninteger of 1 to 4, and is more preferably *—O—, and of is preferably 0,1, 2 or 3 and is more preferably 0 or 1.

Examples of the monomer represented by the formula (a2-1) include themonomers described in JP 2010-204646 A, and the monomers represented bythe formulae (a2-1-1) to (a2-1-6) are prefer able, and the monomersrepresented by the formulae (a2-1-1) to a2-1-4) are more preferable, andthe monomers represented by the formulae (a2-1-1) and (a2-1-3)

When RESIN (A) contains the structural unit derived from the monomerrepresented by the formula (a2-1), the content of the structural unitderived from the monomer represented by the formula (a2-1) is usually 1to 40% by mole based on total molar of all the structural units of RESIN(A), and preferably 1 to 35% by mole, and more preferably 2 to 30% bymole, and still more preferably 2 to 20% by mole.

Examples of the lactone ring of the compound having no acid-labile groupand a lactone ring include a monocyclic lactone ring such asβ-propiolactone ring, γ-butyrolactone ring and γ-valerolactone ring, anda condensed ring formed from a monocyclic lactone ring and the otherring. Among them, preferred are γ-butyrolactone ring and a condensedlactone ring formed from γ-butyrolactone ring and the other ring.

Preferable examples of the monomer having no acid-labile group andhaving a lactone ring include the monomers represented by the formulae(a3-1), (a3-2) and (a3-3):

wherein L^(a4), L^(a5) and L^(a6) each independently represent *—O— or*—O—(CH₂)_(k3)—CO— in which * represents a binding position to —CO— andk3 represents an integer of 1 to 7, R^(a18), R^(a19) and R^(a20) eachindependently represent a hydrogen atom or a methyl group, R^(a21)represents a C1-C4 alkyl group, R^(a22) and R^(a23) are independentlyeach occurrence a carboxyl group, a cyano group or a C1-C4 alkyl group,and p1 represents an integer of 0 to 5, q1 and r1 independently eachrepresent an integer of 0 to 3.

It is preferred that L^(a4), L^(a5) and L^(a6) each independentlyrepresent *—O— or *—O—(CH₂)_(d1)—CO—O— in which * represents a bindingposition to —CO— and d1 represents an integer of 1 to 4, preferably d1is 1, and it is more preferred that L^(a4), L^(a5) and L^(a6) are *—O—.R^(a18), R^(a19) and R^(a20) are preferably methyl groups. R^(a21)preferably a methyl group. It is preferred that R^(a22) and R^(a23) areindependently in each occurrence a carboxyl group, a cyano group or amethyl group. It is preferred that p1 is an integer of 0 to 2, and it ismore preferred that p1 is 0 or 1. It is preferred that q1 and r1independently each represent an integer of 0 to 2, and it is morepreferred that q1 and r1 independently each represent 0 or 1.

Examples of the monomer represented by the formula (a3-1) include themonomers described in JP 2010-204646 A, and the monomers represented bythe formulae (a3-1-1) to (a3-1-4), (a3-2-1) to (a3-2-4) and (a3-3-1) to(a3-3-4), and the monomers represented by the formulae (a3-1-1) to(a3-1-2) and (a3-2-3) to (a3-2-4) are preferable, and the monomersrepresented by the formulae (a3-1-1) and (a3-2-3) are more preferable.

When RESIN (A) contains the structural unit derived from the monomerhaving no acid-labile group and having a lactone ring, the contentthereof is usually 5 to 70% by mole based on total molar of all thestructural units of RESIN (A), and preferably 10 to 65% by mole and morepreferably 15 to 60% by mole.

When RESIN (A) contains the structural unit derived from the monomerrepresented by the formula (a3-1), (a3-2) or (a3-3), the content thereofis usually 5 to 60% by mole based on total molar of all the structuralunits of RESIN (A), and preferably 5 to 50% by mole and more preferably10 to 50% by mole.

RESIN (A) can contain a structural unit derived from a monomer having noacid-labile group and having one or more fluorine atoms.

Examples of the monomer having no acid-labile group and having one ormore fluorine atoms include a monomer represented by the formula (a4-1):

wherein R⁴¹ represents a hydrogen atom or a methyl group, A⁴² representsan optionally substituted C1-C18 aliphatic hydrocarbon group, and A⁴¹represents a group represented by the formula (a4-g1):

A⁴⁰-X⁴⁰_(ss)A⁴³-  (a4-g1)

wherein A⁴⁰ is independently in each occurrence a C1-C5 aliphatichydrocarbon group, A⁴³ represents a C1-C5 aliphatic hydrocarbon group,X⁴⁰ is independently in each occurrence —O—, —CO—, —CO—O— or —O—CO—, andss represents an integer of 0 to 2.

Examples of the C1-C5 aliphatic hydrocarbon group represented by A⁴⁰include the same as those described in A¹⁰ in the formula (a-g1).Examples of the C1-C5 aliphatic hydrocarbon group represented by A⁴³include the same as those described in A¹¹ in the formula (a-g1).

Examples of the group represented by the formula (a4-g1) include thesame as those described in the group represented by the formula (a-g1),

A⁴³ is preferably an ethylene group.

The group represented by the formula (a4-g1) wherein ss is 0 ispreferable, and the group represented by the formula (a4-g1) wherein ssis 0 and A⁴³ is a C1-C6 alkanediyl group is more preferable, and thegroup represented by the formula (a4-g1) wherein ss is 0 and A⁴³ is aC1-C4 alkanediyl group is especially preferable.

The aliphatic hydrocarbon group represented by R⁴² includes a chainaliphatic hydrocarbon group, an alicyclic hydrocarbon group and a groupformed by combining a chain aliphatic hydrocarbon group and an alicyclichydrocarbon group. The aliphatic hydrocarbon group may be saturated orunsaturated, and preferably saturated. Examples of the chain aliphatichydrocarbon group include a C1-C18 alkyl group such as a methyl group,an ethyl group, a propyl group, a butyl group, a pentyl group, a hexylgroup, a heptyl group and an octyl group. The alicyclic hydrocarbongroup may be monocyclic or polycyclic, and examples thereof include amonocyclic alicyclic hydrocarbon group such as a cycloalkyl group suchas a cyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, adimethylcyclohexyl group, a cycloheptyl group and a cyclooctyl group,and a polycyclic alicyclic hydrocarbon group such as a decahydronaphthylgroup, an adamantyl group, a norbornyl group, a methylnorbornyl groupand the following.

wherein * represents a binding position.

The aliphatic hydrocarbon group may be unsubstituted or substituted, andR⁴² is preferably an aliphatic hydrocarbon group having one or moresubstituents. Preferable examples of the substituent include a halogenatom and a group represented by the formula (a-g3):

—X¹²-A¹⁴  (a-g3)

wherein X¹² represents —O—, —CO—, —CO—O— or —O—CO—, and A¹⁴ represents aC3-C17 aliphatic hydrocarbon group optionally having one or more halogenatoms.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom, and a fluorine atom is preferable.Examples of the aliphatic hydrocarbon group include the same as thosedescribed above. Examples of the aliphatic hydrocarbon group having oneor more halogen atoms include a halogenated alkyl group and ahalogenated alicyclic hydrocarbon group such as a halogenated cycloalkylgroup. A perhalogenoalkyl group and a perhalogenocycloalkyl group arepreferable, and a perfluoroalkyl group and a perfluorocycloalkyl groupare more preferable, and a perfluoroalkyl group is still morepreferable. Examples of the perfluoroalkyl group include aperfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group,a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group,a perfluoroheptyl group and a perfluorooctyl group. Among them,preferred is a C1-C6 perfluoroalkyl group, and more preferred is a C1-C3perfluoroalkyl group.

The aliphatic hydrocarbon group represented by R⁴² can have one or moregroups represented by the formula (a-g3), and the total carbon number ofthe aliphatic hydrocarbon group including the carbon number of the grouprepresented by the formula (a-g3) is preferably 15 or less, and morepreferably 12 or less. The aliphatic hydrocarbon group represented byR⁴² preferably has one group represented by the formula (a-g3).

R⁴² is preferably a group represented by the formula (a-g2);

-A¹³-X^(12a)-A^(14a)  (a-g2)

wherein A¹³ represents a C3-C17 aliphatic hydrocarbon group optionallyhaving one or more halogen atoms, X^(12a) represents —CO—O— or —O—CO—,and A^(14a) represents a C3-C17 aliphatic hydrocarbon group optionallyhaving one or more halogen atoms, with the proviso that the total carbonnumber of A¹³, X^(12a), and A^(14a) is 18 or less.

Examples of the aliphatic hydrocarbon group optionally having one ormore halogen atoms represented by A¹³ and A^(14a) include the same asthose described in A¹⁴. The total carbon number of A¹³ and A^(14a) ispreferably 17 or less. The carbon number of A¹³ is preferably 1 to 6,and more preferably 1 to 3. The carbon number of A^(14a) is preferably 4to 15, and more preferably 5 to 12. A^(14a) is preferably a C6-C12alicyclic hydrocarbon group, and more preferably a cyclohexyl group oran adamantyl group.

Examples of the group represented by the formula (a-g2) include thefollowing.

The monomer represented by the formula (a4-1) is preferably a monomerrepresented by the formula (a4-1′):

wherein R⁴¹, A⁴¹, A¹³, X^(12a) and A^(14a) are the same as definedabove, with the proviso that the total carbon number of A¹³ and A^(14a)is 17 or less.

The monomer represented by the formula (a4-1′) is a novel compound, andis useful for a raw material for the synthesis of a resin contained inthe photoresist composition.

It is preferred that A¹³ is a C3-C17 aliphatic hydrocarbon group havingone or more halogen atoms or A^(14a) is a C3-C17 aliphatic hydrocarbongroup having one or more halogen atoms in the formula (a4-1′). It ismore preferred that A¹³ is a C3-C17 aliphatic hydrocarbon group havingone or more halogen atoms, and it is still more preferred that A¹³ is aC3-C17 alkanediyl group having one or more fluorine atoms, and it isespecially preferred that A¹³ is a C3-C17 perfluoroalkanediyl group.

Examples of the monomer represented by the formula (a4-1) include themonomers represented by the formulae (a4-1-1) to (a4-1-22) and (a4-1′-1)to (a4-1′22).

Among them, preferred are the monomers represented by the formulae(a4-1-3), (a4-1-4), (a4-1-7), (a4-1-8), (a4-1-11), (a4-1-12), (a4-1-15),(a4-1-16), (a4-1-19), (a4-1-20), (a4-1-21) and (a4-1-22).

When RESIN (A) contains the structural unit derived from the monomerrepresented by the formula (a4-1), the content thereof is usually 1 to99% by mole based on total molar of all the structural units of RESIN(A), and preferably 2 to 99% by mole and more preferably 3 to 99% bymole.

When RESIN (A) consists of the structural unit derived from the compoundrepresented by the formula (I) and the structural unit derived from themonomer represented by the formula (a4-1), the content of the structuralunit derived from the monomer represented by the formula (a4-1) in RESIN(A) is usually 95 to 99% by mole based on total molar of all thestructural units of RESIN (A), and preferably 96 to 99% by mole and morepreferably 97 to 99% by mole.

RESIN (A) preferably comprises the structural unit derived from thecompound represented by the formula (I), the structural unit derivedfrom a compound having an acid-labile group, and at least one selectedfrom the group consisting of the structural unit derived from thecompound having no acid-labile group and having one or more hydroxylgroups and the structural unit derived from the compound having noacid-labile group and a lactone ring. The compound having an acid-labilegroup is preferably the monomer represented by the formulae (a1-1) or(a1-2), and more preferably the monomer represented by the formulae(a1-1). The compound having no acid-labile group and having one or morehydroxyl groups is preferably the monomer represented by the formula(a2-1), and the compound having no acid-labile group and a lactone ringis preferably the monomer represented by the formula (a3-1) or (a3-2).

Preferable examples of RESIN (A) containing the structural unit derivedfrom the compound having an acid-labile group include the following. Inthe following, the structural units of which RESIN (A) is composed areshown.

RESIN (A) may be a resin consisting of the structural unit derived fromthe compound represented by the formula (I) and the structural unitderived from a compound having no acid-labile group, and examplesthereof include a resin consisting of the structural unit derived fromthe compound represented by the formula (I) and the structural unitderived from a monomer represented by the formula (a4-1). The molarratio of the structural unit derived from the compound represented bythe formula (I) to the structural unit derived from a monomerrepresented by the formula (a4-1) in RESIN (A) (structural unit derivedfrom the compound represented by the formula (I)/the structural unitderived from a monomer represented by the formula (a4-1)) is preferably1/99 to 5/95, and more preferably 1/99 to 4/96 and still more preferably1/99 to 3/97

Examples of RESIN (A) consisting of the structural unit derived from thecompound represented by the formula (I) and the structural unit derivedfrom a monomer represented by the formula (a4-1) include the following.

When the photoresist composition of the present invention contains RESIN(A) consisting of the structural unit derived from the compoundrepresented by the formula (I) and the structural unit derived from amonomer represented by the formula (a4-1), the photoresist compositionof the present invention usually contains a resin comprising astructural unit derived from a monomer having an acid-labile group.Examples of the resin comprising a structural unit derived from amonomer having an acid-labile group include a resin consisting of thestructural unit derived from a compound having an acid-labile group, andat least one selected from the group consisting of the structural unitderived from the compound having no acid-labile group and having one ormore hydroxyl groups and the structural unit derived from the compoundhaving no acid-labile group and a lactone ring, and a resin consistingof the structural unit derived from a compound having an acid-labilegroup, and at least one selected from the group consisting of thestructural unit derived from the compound represented by the formula(I), the structural unit derived from the compound having no acid-labilegroup and having one or more hydroxyl groups and the structural unitderived from the compound having no acid-labile group and a lactonering.

RESIN (A) can be produced according to known polymerization methods suchas radical polymerization.

RESIN (A) usually has 2,500 or more of the weight-average molecularweight, and preferably 3,000 or more of the weight-average molecularweight. RESIN (A) usually has 50,000 or less of the weight-averagemolecular weight, and preferably has 30,000 or less of theweight-average molecular weight. The weight-average molecular weight canbe measured with gel permeation chromatography and can be calculatedbased the results of the chromatography using standard polystyrene.

The photoresist composition of the present invention usually includes80% by mass or more of RESIN (A) based on sum of solid component, andusually includes 99% by mass or less of RESIN (A) based on sum of solidcomponent. In this specification, “solid component” means componentsother than solvent in the photoresist composition.

Next, the photoresist composition of the present invention will beillustrated.

The photoresist composition comprises RESIN (A) and an acid generator.The acid generator is a substance which is decomposed to generate anacid by applying a radiation such as a light, an electron beam or thelike on the substance itself or on a photoresist composition containingthe substance. The acid generated from the acid generator acts on theresin resulting in cleavage of the acid-labile group existing in theresin.

Examples of the acid generator include a nonionic acid generator, anionic acid generator and the combination thereof. Examples of thenonionic acid generator include an organo-halogen compound, a sulfonecompound such as a disulfone, a ketosulfone and a sulfonyldiazomethane,a sulfonate compound such as a 2-nitrobenzylsulfonate, an aromaticsulfonate, an oxime sulfonate, an N-sulfonyloxyimide, asulfonyloxyketone and diazonaphthoquinone 4-sulfonate. Examples of theionic acid generator include an onium salt compound such as a diazoniumsalt, a phosphonium salt, a sulfonium salt and an iodonium salt.Examples of the anion of the onium salt include a sulfonic acid anion, asulfonylimide anion and a sulfonulmethide anion. The onium salt compoundis preferable.

Other examples of the acid generator include acid generators describedin JP 63-26653A, JP55-164824A, JP 62-69263A, JP 63-146038 A, JP63-163452 A, JP 62-153853 A, JP 63-146029 A, U.S. Pat. No. 3,779,778,U.S. Pat. No. 3,849,137, DE Patent No. 3914407 and EP Patent No.126,712.

A fluorine-containing acid generator is preferable.

Preferable examples of the acid generator include a salt represented bythe formula (B1):

wherein Q¹ and Q² each independently represent a fluorine atom or aC1-C6 perfluoroalkyl group,L^(b1) represents a single bond or a C1-C17 saturated divalenthydrocarbon group which can have one or more substituents, and one ormore —CH₂— in the saturated divalent hydrocarbon group can be replacedby —O— or —CO—,Y represents a C1-C18 alkyl group or a C3-C18 alicyclic hydrocarbongroup, and the alkyl group and the cyclic hydrocarbon group can have oneor more substituents, and one or more —CH₂— in the alkyl group and thecyclic hydrocarbon group can be replaced by —O—, —CO— or —SO₂—, andZ⁺ represents an organic cation.

Examples of the C1-C6 perfluoroalkyl group include a trifluoromethylgroup, a pentafluoroethyl group, a heptafluoropropyl group, anonafluorobutyl group, an undecafluoropentyl group and atridecafluorohexyl group, and a trifluoromethyl, group is preferable. Q¹and Q² each independently preferably represent a fluorine atom or atrifluoromethyl group, and Q¹ and Q² are more preferably fluorine atoms.

Examples of the C1-C17 saturated divalent hydrocarbon group include aC1-C17 alkanediyl group, a monocyclic or polycyclic divalent alicyclichydrocarbon group and a group formed by combining two or more groupsselected from the group consisting of the above-mentioned C1-C17alkanediyl, group and the above-mentioned monocyclic or polycyclicdivalent alicyclic hydrocarbon group. Examples of the alkanediyl groupinclude a linear alkanediyl group such as a methylene group, an ethylenegroup, a propane-1,3-diyl group, a butane-1,4-diyl group, apentane-1,5-diyl, a hexane-1,6-diyl group, a heptane-1,7-diyl group, anoctane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diylgroup, an undecane-1,1′-diyl group, a dodecane-1,12-diyl group, atridecane-1,13-diyl group, a tetradecane-1,14-diyl group, apentadecane-1,15-diyl group, a hexadecane-1,16-diyl group, aheptadecane-1,17-diyl group, an ethane-1,1-diyl group, apropane-1,1-diyl group and a propane-2,2-diyl group, a branched chainalkanediyl group formed by replacing one or more hydrogen atom of theabove-mentioned linear alkanediyl group by a C1-C4 alkyl group such as abutane-1,3-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and a2-methylbutane-1,4-diyl group.

Examples of the monocyclic divalent alicyclic hydrocarbon group includea cyclobutane-1,3-diyl group, a cyclopentane-1,3-diyl group, acyclohexane-1,4-diyl group and a cyclooctane-1,5-diyl group, andexamples of the polycyclic divalent alicyclic hydrocarbon group includea norbornane-1,4-diyl group, a norbornane-2,5-diyl group, anadamantane-1,5-diyl group and an adamantane-2,6-diyl group.

One or more —CH₂— in the C1-C17 saturated hydrocarbon group can bereplaced by —O— or —CO—.

Examples of the C1-C17 saturated hydrocarbon group in which One or more—CH₂— are replaced by —O— or —CO— include *—CO—O-L^(b2)-,*—CO—O-L^(b4)-CO—O-L^(b3)-, *-L^(b5)-O—CO—, *—CO—O-L^(b8)-O—, and*—CO—O-L^(b10)-O-L^(b9)-CO—O—, wherein L^(b2) represents a single bondor a C1-C15 divalent saturated hydrocarbon group, L^(b3) represents asingle bond or a C1-C12 divalent saturated hydrocarbon group, L^(b4)represents a single bond or a C1-C13 divalent saturated hydrocarbongroup, with proviso that total carbon number of L^(b3) and L^(b4) is 1to 13, L^(b5) represents a C1-C15 divalent saturated hydrocarbon group,L^(b6) represents a C1-C15 divalent saturated hydrocarbon group, L^(b7)represents a C1-C15 divalent saturated hydrocarbon group, with provisothat total carbon number of L^(b6) and L^(b7) is 1 to 16, L^(b8)represents a C1-C14 divalent saturated hydrocarbon group, L^(b9)represents a C1-C11 divalent saturated hydrocarbon group, L¹⁰ representsa C1-C11 divalent saturated hydrocarbon group, with proviso that totalcarbon number of L^(b9) and L^(b10) is 1 to 12, and * represents abinding position to —C(Q¹)(Q²)-. Among them, preferred is *—CO—O-L^(b)-,and more preferred is *—CO—O-L^(b2)- in which L^(b2) is a single bond or—CH₂—.

Examples of *—CO—O-L^(b2)- include *—CO—O— and *—CO—O—CH₂—. Examples of*—CO—O-L^(b4)-CO—O-L^(b3)- include *—CO—O—CH₂—CO—O—,*—CO—O—(CH₂)₂—CO—O—, *—CO—O—(CH₂)₃—CO—O—; *—CO—O—(CH₂)₄—CO—O—,*—CO—O—(CH₂)₆—CO—O—, *—CO—O—(CH₂)₈—CO—O—, *—CO—O—CH₂—CH(CH₃)—CO—O— and*—CO—O—CH₂—C(CH₃)₂—CO—O—. Examples of *-L^(b5)-O—CO— include*—CH₂—O—CO—, *—(CH₂)₂—O—CO—, *—(CH₂)₃—O—CO—, *—(CH₂)₄—O—CO—,*—(CH₂)₆—O—CO— and *—(CH₂)₈—O—CO—. Examples of *-L^(b7)-O-L^(b6)-include *—CH₂—O—CH₂—. Examples of *—CO—O-L^(b8)-O— include*—CO—O—CH₂—O—, *—CO—O—(CH₂)₂—O—, *—CO—O—(CH₂)₃—O—, *—CO—O—(CH₂)₄— and*—CO—O—(CH₂)₆—O—. Examples of *—CO—O-L^(b10)-O-L^(b9)-CO—O— include thefollowings.

Examples of the substituent in Y include a halogen atom, a hydroxylgroup, an oxo group, a glycidyloxy group, a C2-C4 acyl group, a C1-C12alkoxy group, a C2-C7 alkoxycarbonyl group, a C1-C12 aliphatichydrocarbon group, a C1-C12 hydroxy-containing aliphatic hydrocarbongroup, a C3-C16 saturated cyclic hydrocarbon group, a C6-C18 aromatichydrocarbon group, a C7-C21 aralkyl group and —(CH₂)_(j2)—O—CO—R^(b1)—in which R^(b1) represents a C1-C16 alkyl group, a C3-C16 alicyclichydrocarbon group or a 06-C18 aromatic hydrocarbon group and j2represents an integer of 0 to 4. Examples of the halogen atom include afluorine atom, a chlorine atom, a bromine atom and an iodine atom.Examples of the acyl group include an acetyl group and a propionylgroup, and examples of the alkoxy group include a methoxy group, anethoxy group, a propoxy group, an isopropoxy group and a butoxy group.Examples of the alkoxycarbonyl group include a methoxycarbonyl group, anethoxycarbonyl group, a propoxycarbonyl group, an isopropoxycarbonylgroup and a butoxycarbonyl group. Examples of the alkyl group includethe same as described above. Examples of the hydroxyl-containingaliphatic hydrocarbon group include a hydroxymethyl group. Examples ofthe C3-C16 alicyclic hydrocarbon group include the same as describedabove, and examples of the aromatic hydrocarbon group include a phenylgroup, a naphthyl group, an anthryl group, a p-methylphenyl group, ap-tert-butylphenyl group and a p-adamantylphenyl group. Examples of thearalkyl group include a benzyl group, a phenethyl group, a phenylpropylgroup, a trityl group, a naphthylmethyl group and a naphthylethyl group.

Examples of the C1-C18 alkyl group represented by Y include a methylgroup, an ethyl group, a propyl group, an isopropyl group, a butylgroup, an isobutyl group, a sec-butyl group, a text-butyl group, apentyl group, a neopentyl group, a 1-methylbutyl group, a 2-methylbutylgroup, a 1,2-dimethylpropyl group, a 1-ethylpropyl group, a hexyl group,a 1-methylpentyl group, a heptyl group, an octyl group, a 2-ethylhexylgroup, a nonyl group, a decyl group, an undecyl group and a dodecylgroup, and a C1-C6 alkyl group is preferable. Examples of the C3-C18alicyclic hydrocarbon group represented by Y include the groupsrepresented by the formulae (Y1) to (Y26):

Among them, preferred are the groups represented by the formulae (Y1) to(Y19), and more preferred are the groups represented by the formulae(Y11), (Y14), (Y15) and (Y19), and still more preferred are the groupsrepresented by the formulae (Y11) and (Y14).

Examples of Y having one or more substituents include the followings:

When Y is an alkyl group and L^(b1) is a C1-C17 divalent aliphatichydrocarbon group, one or more —CH₂— in the C1-C17 divalent aliphatichydrocarbon group are preferably replaced by —O— or —CO— and —CH₂— inthe alkyl group is not replaced by —O— or —CO—.

Y is preferably a C3-C18 alicyclic hydrocarbon group which can have oneor more substituents, and more preferably an adamantyl group which canhave one or more substituents, and still more preferably an adamantylgroup, a hydroxyadamantyl group or an oxoadamantyl group.

Among the sulfonic acid anions of the acid generator represented by theformula (31), preferred are anions represented by the formulae (b1-1-1)to (b1-1-9)

wherein Q¹, Q² and L^(b2) are the same as defined above, and R^(b2) andR^(b3) each independently represent the same as the substituent of thealiphatic hydrocarbon group or the alicyclic hydrocarbon grouprepresented by Y. It is preferred that R^(b2) and R^(b3) eachindependently represent a C1-C4 aliphatic hydrocarbon group or ahydroxyl group, and it is more preferred that R^(b2) and R^(b3) eachindependently represent a methyl group or a hydroxyl group.

Examples of the cation part represented by Z⁺ include an organic oniumcation such as a organic sulfonium cation, an organic iodonium cation,an organic ammonium cation, a benzothiazolium cation and an organicphosphonium cation, and an organic sulfonium cation and an organiciodonium cation are preferable, and an, arylsulfonium cation is morepreferable. In this specification, “arylsulfonium cation” means asulfonium cation having at least one aryl group.

Preferable examples of the cation part represented by Z⁺ include thecations represented by the formulae (b2-1) to (b2-4):

wherein R^(b4), R^(b5) and R^(b6) each independently represent a C1-C30alkyl group which can have one or more substituents selected from thegroup consisting of a hydroxyl group, a C1-C12 alkoxy group and a C6-C18aromatic hydrocarbon group, a C3-C18 alicyclic hydrocarbon group whichcan have one or more substituents selected from the group consisting ofa halogen atom, a C2-C4 acyl group and a glycidyloxy group, or a C6-C18aromatic hydrocarbon group which can have one or more substituentsselected from the group consisting of a halogen atom, a hydroxyl group,a C1-C18 aliphatic hydrocarbon group, a C3-C18 alicyclic hydrocarbongroup or a C1-C12 alkoxy group,R^(b7) and R^(b8) are independently in each occurrence a hydroxyl group,a C1-C12 alkyl group or a C1-C12 alkoxy group, m2 and n2 independentlyrepresents an integer of 0 to 5,R^(b9) and R^(b10) each independently represent a C1-C18 alkyl group ora C3-C18 alicyclic hydrocarbon group, or R^(b9) and R^(b10) are bondedto form a C2-C11 divalent acyclic hydrocarbon group which forms a ringtogether with the adjacent S*, and one or more —CH₂— in the divalentacyclic hydrocarbon group may be replaced by —CO—, —O— or —S—,

and

R^(b11) represents a hydrogen atom, a C1-C18 alkyl group, a C3-C18alicyclic hydrocarbon group or a C6-C18 aromatic hydrocarbon group,R^(b12) represents a C1-C12 alkyl, group, a C3-C18 alicyclic hydrocarbongroup or a C6-C18 aromatic hydrocarbon group and the aromatichydrocarbon group can have one or more substituents selected from thegroup consisting of a C1-C12 alkyl group, a C1-C12 alkoxy group, aC3-C18 alicyclic hydrocarbon group and a C2-C13 acyloxy group, orR^(b11) and R^(b12) are bonded each other to form a C1-C10 divalentacyclic hydrocarbon group which forms a 2-oxocycloalkyl group togetherwith the adjacent —CHCO—, and one or more —CH₂— in the divalent acyclichydrocarbon group may be replaced by —CO—, —O— or —S—, andR^(b13), R^(b14), R^(b15), R^(b16), R^(b17) and R^(b18) eachindependently represent a hydroxyl group, a C1-C12 alkyl group or aC1-C12 alkoxy group, L^(b11) represents —S— or —O— and o2, p2, s2 and t2each independently represents an integer of 0 to 5, q2 and r2 eachindependently represents an integer of 0 to 4, and u2 represents 0 or 1.

The alkyl group represented by R^(b9) to R^(b11) has preferably 1 to 12carbon atoms. The alicyclic hydrocarbon group represented by R^(b9) toR^(b11) has preferably 4 to 12 carbon atoms.

Examples of the alkyl group and the aromatic hydrocarbon group includethe same as described above. Preferable examples of the alkyl groupinclude a C1-C12 alkyl group such as a methyl group, an ethyl group, apropyl group, an isopropyl group, a butyl group, a sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, an octyl group and a2-ethylhexyl group. Examples of the alicyclic hydrocarbon group includea cycloalkyl group such as a cyclopentyl group, a cyclohexyl group, acycloheptyl group and a cyclooctyl group, and polycyclic alicyclichydrocarbon group such as a decahydronaphthyl group, an adamantyl group,a norbornyl group, a methylnorbornyl group and the following groups.

Preferable examples of the alicyclic hydrocarbon group include acyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexylgroup, a cycloheptyl group, a cyclodecyl group, a 2-alkyladamantan-2-ylgroup, a 1-(adamantan-1-yl)alkan-1-yl group and an isobornyl group.

Examples of the aromatic group include an aryl group such as a phenylgroup, a p-methylphenyl group, a p-tert-butylphenyl group, ap-adamantylphenyl group, a tolyl group, a xylyl group, a cumyl group, amesityl group, a biphenyl group, an anthryl group, a phenanthryl group,a 2,6-diethylphenyl group, a 2-methyl-6-ethylphenyl group and a naphthylgroup. Preferred are a phenyl group, a p-methylphenyl group, ap-ethylphenyl group, a p-tert-butylphenyl group, a p-cyclohexylphenylgroup, a p-methoxyphenyl group, a biphenyl group and a naphthyl group.

Examples of the aliphatic hydrocarbon group having an aromatichydrocarbon group include a benzyl group, a phenylethyl group, aphenylpropyl group, a trityl group, a naphthylmethyl group and anaphthylethyl group, and a benzyl group is preferable. Examples of thealkoxy group include a methoxy group, an ethoxy group, a propoxy group,an isopropoxy group, a butoxy group, a sec-butoxy group, a tert-butoxygroup, a pentyloxy group, a hexyloxy group, a heptyloxy group, anoctyloxy group, a 2-ethylhexyloxy group, a nonyloxy group, a decyloxygroup, an undecyloxy group and a dodecyloxy group, and a C1-C12 alkoxygroup is preferable.

Examples of the C3-C12 divalent acyclic hydrocarbon group formed bybonding R^(b9) and R^(b0) include a trimethylene group, a tetramethylenegroup and a pentamethylene group. Examples of the ring group formedtogether with the adjacent S⁺ and the divalent acyclic hydrocarbon groupinclude a thiolan-1-ium ring (tetrahydrothiphenium ring), a thian-1-iumring and a 1,4-oxathian-4-ium ring. A C3-C7 divalent a cyclichydrocarbon group is preferable.

Examples of the C1-C10 divalent acyclic hydrocarbon group formed bybonding R^(b11) and R^(b12) include a methylene group, an ethylenegroup, a trimethylene group, a tetramethylene group and a pentamethylenegroup and examples of the ring group include the followings.

A C1-C5 divalent acyclic hydrocarbon group is preferable.

Among the above-mentioned cations, preferred is the cation representedby the formula (b2-1), and more preferred is the cation represented bythe formula (b2-1-1). A triphenylsulfonium cation and atritolylsulfonium cation are especially preferable.

wherein R^(b19), R^(b20) and R^(b21) are independently in eachoccurrence a halogen atom, a hydroxyl group, a C1-C18 alkyl group, aC3-C18 alicyclic hydrocarbon group or a C1-C12 alkoxy group, and one ormore hydrogen atoms of the alkyl group can be replaced by a hydroxylgroup, a C1-C12 alkoxy group or a C6-C18 aromatic hydrocarbon group, andone or more hydrogen atoms of the alicyclic hydrocarbon group can bereplaced by a halogen atom, a glycidyloxy group or a C2-C4 acyl group,and v2, w2 and x² independently each represent an integer of 0 to 5.

The alkyl group has preferably 1 to 12 carbon atoms, and the alicyclichydrocarbon group has preferably 4 to 18 carbon atoms, and v2, w2 and x²independently each preferably represent 0 or 1,

It is preferred that R^(b19), R^(b20) and R^(b21) are independently ineach occurrence a halogen atom, a hydroxyl group, a C1-C12 alkyl groupor a C1-C12 alkoxy group and v2, w2 and x² independently each representan integer of 0 to 5, and it is more preferred that R^(b19), R^(b20) andR^(b21) are independently in each occurrence a fluorine atom, a hydroxylgroup, a C1-C12 alkyl group or a C1-C12 alkoxy group, and v2, w2 and x²independently each preferably represent 0 or 1.

Examples of the cations represented by the formulae (b2-1) to (B2-4) and(b2-1-1) include the cations described in JP 2010-204646 A.

Examples of the salt represented by the formula (B1) include a saltwherein the anion part is any one of the above-mentioned anion and thecation part is any one of the above-mentioned cation. Preferableexamples of the salt include a combination of any one of anionsrepresented by the formulae (b1-1-1) to (b1-1-9) and the cationrepresented by the formulae (b2-1-1), and a combination of any one ofanions represented by the formulae (b1-1-3) to (b1-1-5) and the cationrepresented by the formulae (b2-3)

The salt represented by the formulae (B1-1) to (B1-20) are preferable,and the salt represented by the formulae (B1-1), (B1-2) (B1-3), (B1-6),(B1-7), (81-11), (B1-12), (B1-13) and (B1-14) which contain atriphenylsulfonium cation or a tritolylsulfonium cation are morepreferable.

Two or more kinds of the acid generator can be used in combination.

The content of the acid generator is usually 1 part by mass or more andpreferably 3 parts by mass or more per 100 parts by mass of RESIN (A),and 30 parts by mass or less and preferably 25 parts by mass or less per100 parts by mass of RESIN (A).

The photoresist composition of the present invention can contain one ormore basic compounds, and the content of the basic compound is usually0.01 to 5% by mass based on solid component, preferably 0.01 to 3% bymass, and more preferably 0.01 to 1% by mass. The basic compound has theproperty that it can trap an acid, especially an acid generated from theacid generator by applying a radiation.

The basic compound is preferably a basic nitrogen-containing organiccompound, and examples thereof include an ammonium salt and an aminecompound such as an aliphatic amine and an aromatic amine. Examples ofthe aliphatic amine include a primary amine, a secondary amine and atertiary amine. Examples of the aromatic amine include an aromatic aminein which aromatic ring has one or more amino groups such as aniline anda heteroaromatic amine such as pyridine. Preferable examples thereofinclude an aromatic amine represented by the formula (C2):

wherein Ar^(c1) represents an aromatic hydrocarbon group, and R^(c5) andR^(c6) each independently represent a hydrogen atom, a C1-C6 alkylgroup, a C5-C10 alicyclic hydrocarbon group or a C6-C10 aromatichydrocarbon group, and the alkyl group and the alicyclic hydrocarbongroup can have one or more substituents selected from the groupconsisting of a hydroxyl group, an amino group, an amino group havingone oz two C1-C4 alkyl groups and a C1-C6 alkoxy group, and the aromatichydrocarbon group can have one or more substituents selected from thegroup consisting of a C1-C6 alkyl group, a C5-C10 alicyclic hydrocarbongroup, a C6-C10 aromatic hydrocarbon group and a C1-C6 alkoxy group.

As the aromatic amine represented by the formula (C2), an aminerepresented by the formula (C2-1):

wherein R^(c5) and R^(c6) are the same as defined above, and R^(c7) isindependently in each occurrence a C1-C6 alkyl group, a C1-C6 alkoxygroup, a C5-C10 alicyclic hydrocarbon group or a C6-C10 aromatichydrocarbon group, and m3 represents an integer of 0 to 3, ispreferable. The alicyclic hydrocarbon group is preferably a cycloalkylgroup.

An ammonium salt represented by the formula (C2-2):

wherein R^(c8′), R^(c9′), R^(c10′), and R^(c11′) each independentlyrepresent an alkyl group, an alicyclic hydrocarbon group or an aromatichydrocarbon group, and the alkyl group, the alicyclic hydrocarbon groupand the aromatic hydrocarbon group can have one or more substituentsselected from the group consisting of a hydroxyl group, an amino group,an amino group having one or two C1-C4 alkyl groups and a C1-C6 alkoxygroup, and An represents OH⁻, is also preferable. The alkyl group haspreferably 1 to 6 carbon atoms, and the alicyclic hydrocarbon group haspreferably 3 to 6 carbon atoms, and the aromatic hydrocarbon group haspreferably 6 to 10 carbon atoms.

Examples of the aromatic amine represented by the formula (C2) include1-naphthylamine, 2-naphthylamine, aniline, diisopropylaniline,2-methylaniline, 3-methylaniline, 4-methylaniline, 4-nitroaniline,N-methylaniline, N,N-dimethylaniline, and diphenylamine, and among them,preferred is diisopropylaniline and more preferred is2,6-diisopropylaniline. Examples of the ammonium salt represented by theformula (C2-2) include tetramethylammonium hydroxide andtetrabutylammonium hydroxide.

Other examples of the basic compound include amines represented by theformulae (C3) to (C11):

wherein R^(c8), R^(c20), R^(c21), and R^(a23) to R^(c28) eachindependently represent an alkyl group, an alkoxy group, an alicyclichydrocarbon group or an aromatic hydrocarbon group, and the alkyl group,the alkoxy group, the alicyclic hydrocarbon group and the aromatichydrocarbon group can have one or more substituents selected from thegroup consisting of a hydroxyl group, an amino group, an amino grouphaving one or two C1-C4 alkyl groups and a C1-C6 alkoxy group, R^(c9),R^(c10), R^(c11) to R^(c14), R^(c16) to R^(c19), and R^(c22) eachindependently represents a hydrogen atom, an alkyl group, an alicyclichydrocarbon group or an aromatic hydrocarbon group, and the alkyl group,the alicyclic hydrocarbon group and the aromatic hydrocarbon group canhave one or more substituents selected from the group consisting of ahydroxyl group, an amino group, an amino group having one or two C1-C4alkyl groups and a C1-C6 alkoxy group,R^(c15) is independently in each occurrence an alkyl group, an alicyclichydrocarbon group or an alkanoyl group,L^(c1) and L^(c2) each independently represents a divalent aliphatichydrocarbon group, —CO—, —C(═NH)—, —C(═NR^(c3))—, —S—, —S—S— or acombination thereof and R^(c3) represents a C1-C4 alkyl group, O3 to u3each independently represents an integer of 0 to 3 and n3 represents aninteger of 0 to 8.

The alkyl group has preferably 1 to 6 carbon atoms, and the alicyclichydrocarbon group has preferably 3 to 6 carbon atoms, and the alkanoylgroup has preferably 2 to 6 carbon atoms, and the divalent aliphatichydrocarbon group has preferably 1 to 6 carbon atoms. The divalentaliphatic hydrocarbon group is preferably an alkylene group.

Examples of the amine represented by the formula (C3) includehexylamine, heptylamine, octylamine, nonylamine, decylamine,dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine,dinonylamine, didecylamine, triethylamine, trimethylamine,tripropylamine, tributylamine, tripentylamine, trihexylamine,triheptylamine, trioctylamine, trinonylamine, tridecylamine,methyldibutylamine, methyldipentylamine, methyldihexylamine,methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine,methyldinonylamine, methyldidecylamine, ethyldibutylamine,ethydipentylamine, ethyldihexylamine, ethydiheptylamine,ethyldioctylamine, ethyldinonylamine, ethyldidecylamine,dicyclohexylmethylamine, tris[2-(2-methoxyethoxy)ethyl]amine,triisopropanolamine, ethylenediamine, tetramethylenediamine,hexamethylenediamine, 4,4′-diamino-1,2-diphenylethane,4,4′-diamino-3,3′-dimethyldiphenylmethane and4,4′-diamine-3,3′-diethyldiphenylmethane.

Examples of the amine represented by the formula (C4) includepiperazine. Examples of the amine represented by the formula (C5)include morpholine. Examples of the amine represented by the formula(C6) include piperidine and hindered amine compounds having a piperidineskeleton as disclosed in JP 11-52575 A. Examples of the aminerepresented by the formula (C7) include 2,2′-methylenebisaniline.Examples of the amine represented by the formula (C8) include imidazoleand 4-methylimidazole. Examples of the amine represented by the formula(C9) include pyridine and 4-methylpyridine. Examples of the aminerepresented by the formula (C10) include di-2-pyridyl ketone,1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane,1,3-di(4-pyridyl)propane, 1,2-bis(2-pyridyl)ethene,1,2-bis(4-pyridyl)ethene, 1,2-di(4-pyridyloxy)ethane, 4,4′-dipyridylsulfide, 4,4′-dipyridyl disulfide, 2,2′-dipyridylamine and2,2′-dipicolylamine. Examples of the amine represented by the formula(C11) include bipyridine.

The photoresist composition of the present invention usually containsone or more solvents. Examples of the solvent include a glycol etherester such as ethyl cellosolve acetate, methyl cellosolve acetate andpropylene glycol monomethyl ether acetate; a glycol ether such aspropylene glycol monomethyl ether; an acyclic ester such as ethyllactate, butyl acetate, amyl acetate and ethyl pyruvate; a ketone suchas acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone; and acyclic ester such as γ-butyrolactone.

The amount of the solvent is usually 90% by mass or more, preferably 92%by mass or more preferably 94% by mass or more based on total amount ofthe photoresist composition of the present invention. The amount of thesolvent is usually 99.9% by mass or less based on total amount of thephotoresist composition of the present invention, and preferably 99% bymass or less. The photoresist composition containing a solvent can bepreferably used for producing a thin layer photoresist pattern.

The photoresist composition of the present invention can contain, ifnecessary, a small amount of various additives such as a sensitizer, adissolution inhibitor, other polymers, a surfactant, a stabilizer and adye as long as the effect of the present invention is not prevented.

The photoresist composition of the present invention is useful for achemically amplified photoresist composition.

A photoresist pattern can be produced by the following steps (1) to (5)

(1) a step of applying the photoresist composition of the presentinvention on a substrate,

(2) a step of forming a photoresist film by conducting drying,

(3) a step of exposing the photoresist film to radiation,

(4) a step of baking the exposed photoresist film, and

(5) a step of developing the baked photoresist film with an alkalinedeveloper, thereby forming a photoresist pattern.

The applying of the photoresist composition on a substrate is usuallyconducted using a conventional apparatus such as spin coater. Thephotoresist composition is preferably filtrated with filter having 0.003to 0.2 μm of a pore size before applying. Examples of the substrateinclude a silicon wafer or a quartz wafer on which a sensor, a circuit,a transistor or the like is formed.

The formation of the photoresist film is usually conducted using aheating apparatus such as hot plate or a decompressor, and the heatingtemperature is usually 50 to 200° C., and the operation pressure isusually 1 to 1.0*10⁵ Pa.

The photoresist film obtained is exposed to radiation using an exposuresystem. The exposure is usually conducted through a mask having apattern corresponding to the desired photoresist pattern. Examples ofthe exposure source include a light source radiating laser light in aUV-region such as a KrF excimer laser (wavelength; 248 nm), an ArFexcimer laser (wavelength; 193 nm) and a F₂ laser (wavelength: 157 nm),and a light source radiating harmonic laser light in a far UV region ora vacuum UV region by wavelength conversion of laser light from a solidlaser light source (such as YAG or semiconductor laser). Other examplesof the exposure source include EUV (extreme ultraviolet) and EB(electron beam).

The temperature of baking of the exposed photoresist film is usually 50to 200° C., and preferably 70 to 150° C.

The development of the baked photoresist film is usually carried outusing a development apparatus. The alkaline developer used may be anyone of various alkaline aqueous solution used in the art. Generally, anaqueous solution of tetramethylammonium hydroxide or(2-hydroxyethyl)trimethylammonium hydroxide (commonly known as“choline”) is often used. After development, the photoresist patternformed is preferably washed with ultrapure water, and the remained wateron the photoresist pattern and the substrate is preferably removed.

The photoresist composition of the present invention provides aphotoresist pattern in a good focus margin, and therefore, thephotoresist composition of the present invention is suitable for ArFexcimer laser lithography, KrF excimer laser lithography, EUV (extremeultraviolet) lithography, EUV immersion lithography and EB (electronbeam) lithography, and the photoresist composition of the presentinvention is especially suitable for immersion lithography.

EXAMPLES

The present invention will be described more specifically by Examples,which are not construed to limit the scope of the present invention.

The “%” and “part(s)” used to represent the content of any component andthe amount of any material used in the following examples andcomparative examples are on a weight basis unless otherwise specificallynoted. The weight-average molecular weight of any material used in thefollowing examples is a value found by gel permeation chromatography[Column (Three Columns with guard column): TSK gel Multipore HXL-M,manufactured by TOSOH CORPORATION, Solvent: Tetrahydrofuran, Flow rate:1.0 mL/min., Detector: RI detector, Column temperature: 40° C.,Injection volume: 100 μL] using standard polystyrene, manufactured byTOSOH CORPORATION, as a standard reference material.

Synthesis Example 1

A mixture prepared by mixing 8.50 parts of a compound represented by theformula (I1-2), 34.00 parts of tetrahydrofuran and 6.20 parts ofpyridine was stirred at 23° C. for 30 minutes. To the mixture, 7.25parts of a compound represented by the formula (I1-1) was added. Theresultant mixture was stirred at 40° C. for 3 hours. To the reactionmixture obtained, added were 240 parts of ethyl acetate and 17.16 partsof 5% hydrochloric acid. The mixture was stirred at 23° C. for 30minutes and then, separated. The organic layer obtained was mixed with60 parts of aqueous saturated sodium hydrogen carbonate solution. Themixture obtained was stirred at 23° C. for 30 minutes and then,separated. The organic layer obtained was mixed with 60 parts ofion-exchanged water. The mixture obtained was stirred at 23° C. for 30minutes and then, separated. This washing was repeated five times. Theorganic layer obtained was concentrated. The residue was purified withcolumn chromatography (silica gel 60-200 mesh available from Merck KGaA,Developing solvent: ethyl acetate) to obtain 6.28 parts of a monomerrepresented by the formula (I1), which is called as Monomer (I1).

MS (Mass Analysis): 464.1 (molecular ion peak)

Synthesis Examples 2

A mixture prepared by mixing 8.50 parts of a compound represented by theformula (I3-2), 34.00 parts of tetrahydrofuran and 6.20 parts ofpyridine was stirred at 23° C. for 30 minutes. To the mixture, 5.62parts of a compound represented by the formula (I3-1) was added. Theresultant mixture was stirred at 40° C. for 3 hours. To the reactionmixture obtained, added were 200 parts of ethyl acetate and 20 parts of5% hydrochloric acid. The mixture was stirred at 23° C. for 30 minutesand then, separated. The organic layer obtained was mixed with 60 partsof aqueous saturated sodium hydrogen carbonate solution. The mixtureobtained was stirred at 23° C. for 30 minutes and then, separated. Theorganic layer obtained was mixed with 60 parts of ion-exchanged water.The mixture obtained was stirred at 23° C. for 30 minutes and then,separated. This washing was repeated five times. The organic layerobtained was concentrated. The residue was purified with columnchromatography (silica gel 60-200 mesh available from Merck KGaA,Developing solvent: ethyl acetate) to obtain 5.88 parts of a monomerrepresented by the formula (I3), which is called as Monomer (I3).

MS (Mass Analysis): 414.1 (molecular ion peak)

In Examples and Resin Synthesis Examples, the monomer represented by theformula (a1-1-1) which is called as Monomer (a1-1-1), the monomerrepresented by the formula (a1-1-2) which is called as Monomer (a1-1-2),the monomer represented by the formula (a1-1-3) which is called asMonomer (a1-1-3), the monomer represented by the formula (a1-2-3) whichis called as Monomer (a1-2-3), the monomer represented by the formula(a1-2-9) which is called as Monomer (a1-2-9), the monomer represented bythe formula (a1-5-1) which is called as Monomer (a1-5-1), the monomerrepresented by the formula (a2-1-1) which is called as Monomer (a2-1-1)the monomer represented by the formula (a3-1-1) which is called asMonomer (a3-1-1), the monomer represented by the formula (a3-2-1) whichis called as Monomer (a3-2-1), the monomer represented by the formula(a3-2-3) which is called as Monomer (a3-2-3), the monomer represented bythe formula (D) which is called as Monomer (D), Monomer (I1) and Monomer(I3).

Example 1

Monomers (a1-1-3), (a1-2-3), (a2-1-1), (a3-1-1), (a3-2-3) and (I1) weremixed in a molar ratio of 30/11/6/20/30/3 (Monomer (a1-1-3)/Monomer(a1-2-3)/Monomer (a2-1-1)/Monomer (a3-1-1)/Monomer (a3-2-3)/Monomer(I1)), and 1,4-dioxane in 1.5 times part based on total parts of allmonomers was added to prepare a solution. To the solution,azobisisobutyronitrile as an initiator in a ratio of 1 mol % based onall monomer molar amount and azobis(2,4-dimethylvaleronitrile) as aninitiator in a ratio of 3 mol % based on all monomer molar amount wereadded, and the obtained mixture was heated at 73° C. for about 5 hours.The reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas collected by filtration and then, was dissolved in 1,4-dioxanefollowed by poured the resultant solution into a large amount of amixture of methanol and water to cause precipitation. This operation wasrepeated twice for purification. As a result, a resin having aweight-average molecular weight of about 2.8×10⁴ was obtained in a yieldof 55%. This resin is called as resin A1. Resin A1 had the followingstructural units.

Example 2

Monomers (a1-1-2), (a2-1-1), (a3-1-1) and (I1) were mixed in a molarratio of 47/25/25/3 (Monomer (a1-1-2)/Monomer (a2-1-1)/Monomer(a3-1-1)/Monomer (I1)), and 1,4-dioxane in 1.5 times part based on totalparts of all monomers was added to prepare a solution. To the solution,azobisisobutyronitrile as an initiator in a ratio of 1 mol % based onall monomer molar amount and azobis(2,4-dimethylvaleronitrile) as aninitiator in a ratio of 3 mol % based on all monomer molar amount wereadded, and the obtained mixture was heated at 80° C. for about 8 hours.The reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas collected by filtration and then, was dissolved in 1,4-dioxanefollowed by poured the resultant solution into a large amount of amixture of methanol and water to cause precipitation. This operation wasrepeated twice for purification. As a result, a resin having aweight-average molecular weight of about 3.2×10⁴ was obtained in a yieldof 67%. This resin is called as resin A2. Resin A2 had the followingstructural units.

Resin Synthesis Example 1

Monomer (a1-1-2), Monomer (a2-1-1) and Monomer (a3-1-1) were mixed at amolar ratio of 50:25:25 (Monomer (a1-1-2):Monomer (a2-1-1):monomer(a3-1-1)), and 1,4-dioxane in 1.5 times mass based on the total amountof all monomers was added thereto. To the resultant mixture,azobisisobutyronitrile as an initiator in a ratio of 1 mol % based onall monomer molar amount, and azobis(2,4-dimethylvaleronitrile) as aninitiator in a ratio of 3 mol % based on all monomer molar amount wereadded. The obtained mixture was heated at 80° C. for about 8 hours.Then, the reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas isolated by filtration and dissolved in 1,4-dioxane. The resultantsolution was poured into a large amount of a mixture of methanol andwater to cause precipitation, and this operation was repeated twice forpurification. As a result, a resin having a weight-average molecularweight of about 9.2×10³ was obtained in a yield of 60%. This is calledas Resin A3. Resin A3 had the following structural units.

Resin Synthesis Example 2

Monomer (a1-1-1), Monomer (a1-2-9) and Monomer (a3-2-1) were mixed at amolar ratio of 36; 34:30 (Monomer (a1-1-1):Monomer (a1-2-9):Monomer(a3-2-1)), and 1,4-dioxane in 1.5 times mass based on the total amountof all monomers was added thereto. To the resultant mixture,azobisisobutyronitrile as an initiator in a ratio of 1.5 mol % based onall monomer molar amount, and azobis(2,4-dimethylvaleronitrile) as aninitiator in a ratio of 4.5 mol % based on all monomer molar amount wereadded. The obtained mixture was heated at 75° C. for about 5 hours.Then, the reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas isolated by filtration and dissolved in 1,4-dioxane. The resultantsolution was poured into a large amount of a mixture of methanol andwater to cause precipitation, and this operation was repeated twice forpurification. As a result, a resin having a weight-average molecularweight of about 5.0×10³ was obtained in a yield of 48%. This is calledas Resin A4. Resin A4 had the following structural units.

Resin Synthesis Example 3

Monomer (a1-2-9) and Monomer (D) were mixed at a molar ratio of 70:30(Monomer (a1-2-9):Monomer (D)), and 1,4-dioxane in 1.5 times mass basedon the total amount of all monomers was added thereto. To the resultantmixture, azobisisobutyronitrile as an initiator in a ratio of 1 mol %based on all monomer molar amount, and azobis(2,4-dimethylvaleronitrile)as an initiator in a ratio of 3 mol % based on all monomer molar amountwere added. The obtained mixture was heated at 75° C. for about 5 hours.Then, the reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas isolated by filtration and dissolved in 1,4-dioxane. The resultantsolution was poured into a large amount of a mixture of methanol andwater to cause precipitation, and this operation was repeated twice forpurification. As a result, a resin having a weight-average molecularweight of about 6.7×10 was obtained in a yield of 58%. This is called asResin A5. Resin A5 had the following structural units.

Example 3

Monomers (a1-1-3), (a1-2-3), (a2-1-1), (a3-1-1), (a3-2-3) and (I1) weremixed in a molar ratio of 30/11/6/30/20/3 (Monomer (a1-1-3)/Monomer(a1-2-3)/Monomer (a2-1-1)/Monomer (a3-1-1)/Monomer (a3-2-3)/Monomer(I1)), and 1,4-dioxane in 1.5 times part based on total parts of allmonomers was added to prepare a solution. To the solution,azobisisobutyronitrile as an initiator in a ratio of 1 mol % based onall monomer molar amount and azobis(2,4-dimethylvaleronitrile) as aninitiator in a ratio of 3 mol % based on all monomer molar amount wereadded, and the obtained mixture was heated at 73° C. for about 5 hours.The reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas collected by filtration and then, was dissolved in 1,4-dioxanefollowed by poured the resultant solution into a large amount of amixture of methanol and water to cause precipitation. This operation wasrepeated twice for purification. As a result, a resin having aweight-average molecular weight of about 2.9×10⁴ was obtained in a yieldof 53%. This resin is called as resin A6, Resin A6 had the followingstructural units.

Example 4

monomers (a1-1-3), (a1-5-1), (a2-1-1), (a3-1-1), (a3-2-3) and (I1) weremixed in a molar ratio of 30/11/6/30/20/3 (Monomer (a1-1-3)/Monomer(a1-5-1)/Monomer (a2-1-1)/Monomer (a3-1-1)/Monomer (a3-2-3)/Monomer(I1)), and 1,4-dioxane in 1.5 times part based on total parts of allmonomers was added to prepare a solution. To the solution,azobisisobutyronitrile as an initiator in a ratio of 1 mol % based onall monomer molar amount and azobis(2,4-dimethylvaleronitrile) as aninitiator in a ratio of 3 mol % based on all monomer molar amount wereadded, and the obtained mixture was heated at 73° C. for about 5 hours.The reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas collected by filtration and then, was dissolved in 1,4-dioxanefollowed by poured the resultant solution into a large amount of amixture of methanol and water to cause precipitation. This operation wasrepeated twice for purification. As a result, a resin having aweight-average molecular weight of about 2.5×10⁴ was obtained in a yieldof 56%. This resin is called as resin A7. Resin A7 had the followingstructural units.

Example 5

Monomers (a1-1-3), (a1-2-3), (a2-1-1), (a3-1-1), (a3-2-3) and (I3) weremixed in a molar ratio of 30/11/6/30/20/3 (Monomer (a1-1-3)/Monomer(a1-2-3)/Monomer (a2-1-1)/Monomer (a3-1-1)/Monomer (a3-2-3)/Monomer(I3)), and 1,4-dioxane in 1.5 times part based on total parts of allmonomers was added to prepare a solution. To the solution,azobisisobutyronitrile as an initiator in a ratio of 1 mol % based onall monomer molar amount and azobis(2,4-dimethylvaleronitrile) as aninitiator in a ratio of 3 mol % based on all monomer molar amount wereadded, and the obtained mixture was heated at 73° C. for about 5 hours.The reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas collected by filtration and then, was dissolved in 1,4-dioxanefollowed by poured the resultant solution into a large amount of amixture of methanol and water to cause precipitation. This operation wasrepeated twice for purification. As a result, a resin having aweight-average molecular weight of about 3.1×10⁴ was obtained in a yieldof 59%. This resin is called as resin A8. Resin A8 had the followingstructural units.

Example 6

Monomers (a1-1-3), (a1-5-1) (a2-1-1), (a3-1-1) (a3-2-3) and (I3) weremixed in a molar ratio of 30/11/6/30/20/3 (Monomer (a1-1-3)/Monomer(a1-5-1)/Monomer (a2-1-1)/Monomer (a3-1-1)/Monomer (a3-2-3)/Monomer(I3)), and 1,4-dioxane in 1.5 times part based on total parts of allmonomers was added to prepare a solution. To the solution,azobisisobutyronitrile as an initiator in a ratio of 1 mol % based onall monomer molar amount and azobis(2,4-dimethylvaleronitrile) as aninitiator in a ratio of 3 mol % based on all monomer molar amount wereadded, and the obtained mixture was heated at 73° C. for about 5 hours.The reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas collected by filtration and then, was dissolved in 1,4-dioxanefollowed by poured the resultant solution into a large amount of amixture of methanol and water to cause precipitation. This operation wasrepeated twice for purification. As a result, a resin having aweight-average molecular weight of about 2.9×10⁴ was obtained in a yieldof 61%. This resin is called as resin A9. Resin A9 had the followingstructural units.

Examples 7 to 13 and Comparative Examples 1 to 2 <Resin> Resin A1, A2,A3, A4, A5, A6, A7, A8, A9 <Acid Generator>

B1: salt represented by the following formula

B2: Salt represented by the following formula

<Basic Compound>

C1: 2,6-diisopropylaniline

<Solvent>

E1: propylene glycol monomethyl ether acetate 265 parts propylene glycolmonomethyl ether 20.0 parts γ-butyrolactone  3.5 parts 2-heptanone 20.0parts

The following components were mixed and dissolved, further, filtratedthrough a fluorine resin filter having pore diameter of 0.2 μm, toprepare photoresist compositions.

Resin (kind and amount are described in Table 1)

Acid generator (kind and amount are described in Table 1)

Basic compound (kind and amount are described in Table 1)

Solvent E1

TABLE 1 Basic Resin Acid Generator Compound (kind/amount (kind/amount(kind/amount PB PEB (part)) (part)) (part)) (° C.) (° C.) Ex. 7 A1/10B1/1.20 C1/0.07 100 85 Ex. 8 A2/10 B1/1.20 C1/0.07 110 95 Ex. 9 A2/10B2/1.20 C1/0.07 110 95 Ex. 10 A6/10 B1/1.20 C1/0.07 100 85 Ex. 11 A7/10B1/1.20 C1/0.07 100 85 Ex. 12 A8/10 B1/1.20 C1/0.07 100 85 Ex. 13 A9/10B1/1.20 C1/0.07 100 85 Comp. A5/0.3 B2/1.20 C1/0.07 110 95 Ex. 1 A4/10Comp. A3/10 B2/1.20 C1/0.07 110 95 Ex. 2

Silicon wafers (12 inches) were each coated with “ARC-29”, which is anorganic anti-reflective coating composition available from NissanChemical Industries, Ltd., and then baked under the conditions; 205° C.,60 seconds, to form a 78 nm-thick organic anti-reflective coating. Eachof the photoresist compositions prepared in Examples 7 to 13 andComparative Examples 1 to 2 was spin-coated over the anti-reflectivecoating so that the thickness of the resulting film became 85 μm afterdrying. The silicon wafers thus coated with the respective photoresistcompositions were each prebaked on a direct hotplate at a temperatureshown in column of “PB” of Table 1 for 60 seconds. Using an ArF excimerlaser stepper for immersion exposure (“XT:1900Gi” manufactured by ASML,NA=1.35, 3/4 Annular X-Y polarization), each wafer thus formed with therespective resist film was subjected to contact hole pattern exposureusing a photomask for forming a contact hole pattern having 100 nm of ahole pitch and 70 nm of a hole diameter with the exposure quantity beingvaried stepwise. As the immersion medium, ultrapure water was used.

After the exposure, each wafer was subjected to post-exposure baking ona hotplate at a temperature shown in column of “PM” of Table 1 for 60seconds and then to paddle development for 60 seconds with an aqueoussolution of 2.38 wt % tetramethylammonium hydroxide.

Each of line and space patterns developed on the organic anti-reflectivecoating substrate after the development was observed with a scanningelectron microscope, the results of which are shown in Table 2.

Effective sensitivity (ES): It was expressed as the amount Of exposurethat the hole diameter of the contact hole pattern became 55 nm afterexposure and development.

Focus margin (DOE); The photoresist patterns were obtained at theexposure amount of ES, with the focal point distance being variedstepwise. Each of patterns developed on the organic anti-reflectivecoating substrate after the development were observed and the focalpoint distances when the patterns of which hole diameter was within 55nm±5% (about 52.5 to 57.7 nm) were measured and the difference betweenthe max value of the focal point distance and the minimum value of thefocal point distance was calculated. When the difference is 0.21 μm ormore, DOF is very good and its evaluation is marked by “⊚”, when thedifference is 0.15 μm or more and less than 0.21 μm, DOF is good and itsevaluation is marked by “◯”, and when the difference is less than 0.15μm, DOF is bad and its evaluation is marked by “X”. Further, each of thedifferences is also shown in parentheses in a column of “DOF”. Thedifference is bigger, the better focus margin the photoresistcomposition has.

TABLE 2 DOF Ex. 7 ⊚ (0.24 nm) Ex. 8 ⊚ (0.21 nm) Ex. 9 ◯ (0.15 nm) Ex. 10⊚ (0.24 nm) Ex. 11 ⊚ (0.24 nm) Ex. 12 ⊚ (0.24 nm) Ex. 13 ⊚ (0.24 nm)Comp. Ex. 1 X (0.06 nm) Comp. Ex. 2 X (0.12 nm)

The photoresist composition of the present invention provides a goodresist pattern having good focus margin, and is suitable for ArF excimerlaser lithography, EUV lithography and EB lithography, especiallysuitable for immersion lithography.

1. A resin comprising a structural unit derived from a compoundrepresented by the formula (I):

wherein R¹ represents a hydrogen atom or a methyl group, A² represents adivalent fluorine-containing C1-C12 hydrocarbon group, and A¹ representsa group represented by the formula (a-g1):A¹⁰-X¹⁰_(s)A¹¹-  (a-g1) wherein A¹⁰ is independently in eachoccurrence a C1-C5 aliphatic hydrocarbon group, A¹¹ represents a C1-C5aliphatic hydrocarbon group, X¹⁰ is independently in each occurrence—O—, —CO—, —CO—O— or —O—CO—, and s represents an integer of 0 to
 2. 2.The resin according to claim 1, wherein s is 0 in the formula (a-g1). 3.The resin according to claim 1, wherein A¹¹ is a C1-C6 alkanediyl groupin the formula (a-g1).
 4. The resin according to claim 1, wherein A¹¹ isan ethylene group in the formula (a-g1).
 5. The resin according to claim1, wherein A² is a C1-C3 perfluoroalkanediyl group in the formula (I).6. The resin according to claim 1, which further comprises a structuralunit derived from a compound having an acid-labile group.
 7. The resinaccording to claim 6, wherein the compound having an acid-labile groupis a monomer represented by the formula (a1-1) or (a1-2):

wherein R^(a4) and R^(a5) each independently represents a hydrogen atomor a methyl group, R^(a6) and R^(a7) each independently represents aC1-C8 alkyl group or a C3-C10 alicyclic hydrocarbon group, L^(a1) andL^(a2) each independently represents *—O— or *—O—(CH₂)_(k1)—CO—O— inwhich * represents a binding position to —CO—, and k1 represents aninteger of 1 to 7, and m1 represents an integer of 0 to 14, n1represents an integer of 0 to 10, and n1′ represents an integer of 0 to3.
 8. The resin according to claim 1, which further comprises astructural unit derived from a compound having no acid-labile group andhaving a hydroxyladamantyl group.
 9. The resin according to claim 8,wherein the compound having no acid-labile group and having ahydroxyladamantyl group is a monomer represented by the formula (a2-1):

wherein R^(a14) represents a hydrogen atom or a methyl group, R^(a15)and R^(a16) each independently represent a hydrogen atom, a methyl groupor a hydroxyl group, L^(a3) represents *—O— or *—O—(CH₂)_(k2)—CO—O— inwhich * represents a binding position to —CO—, and k2 represents aninteger of 1 to 7, and of represents an integer of 0 to
 10. 10. Theresin according to claim 1, which further comprises a structural unitderived from a monomer having no acid-labile group and having a lactonering.
 11. The resin according to claim 10, wherein the monomer having noacid-labile group and having a lactone ring is a monomer represented bythe formula (a3-1), (a3-2) or (a3-3):

wherein L^(a4), L^(a5) and L^(a6) each independently represent *—O— or*—O—(CH₂)_(k3)—CO—O— in which * represents a binding position to —CO—and k3 represents an integer of 1 to 7, R^(a18), R^(a19) and R^(a20)each independently represent a hydrogen atom or a methyl group, R^(a21)represents a C1-C4 alkyl group, R^(a22) and R^(a23) are independently ineach occurrence a carboxyl group, a cyano group or a C1-C4 alkyl group,and p1 represents an integer of 0 to 5, q1 and r1 independently eachrepresent an integer of 0 to
 3. 12. The resin according to claim 1,which further comprises a structural unit derived from a monomer havingno acid-labile group and having one or more fluorine atoms.
 13. Theresin according to claim 12, wherein the monomer having no acid-labilegroup and having one or more fluorine atoms is a monomer represented bythe formula (a4-1):

wherein R⁴¹ represents a hydrogen atom or a methyl group, A⁴² representsan optionally substituted C1-C18 aliphatic hydrocarbon group, and A⁴¹represents a group represented by the formula (a4-g1):A⁴⁰-X⁴⁰_(ss)A⁴³-  (a4-g1) wherein A⁴⁰ is independently in eachoccurrence a C1-C5 aliphatic hydrocarbon group, A⁴³ represents a C1-C5aliphatic hydrocarbon group, X⁴⁰ is independently in each occurrence—O—, —CO—, —CO—O— or —O—CO—, and ss represents an integer of 0 to
 2. 14.A photoresist composition comprising the resin according to claim 1 andan acid generator.
 15. The photoresist composition according to claim14, which further comprises a solvent.
 16. A process for producing aphotoresist pattern comprising the following steps (1) to (5): (1) astep of applying the photoresist composition according to claim 14 or 15on a substrate, (2) a step of forming a photoresist film by conductingdrying, (3) a step of exposing the photoresist film to radiation, (4) astep of baking the exposed photoresist film, and (5) a step ofdeveloping the baked photoresist film with an alkaline developer,thereby forming a photoresist pattern.